Problem: $ { \left[\begin{array}{rrr}{2} & {1} & {3} \\ {-1} & {-2} & {0}\end{array}\right]+\left[\begin{array}{rrr}{0} & {3} & {0} \\ {0} & {4} & {-1}\end{array}\right] = {?} } $
Answer: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rrr}{2}+{0} & {1}+{3} & {3}+{0} \\ {-1}+{0} & {-2}+{4} & {0}+{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{2} & {4} & {3} \\ {-1} & {2} & {-1}\end{array}\right]}$